Poly(lactic acid)-based Nanocomposite for Construction of Efficient Bilirubin Oxidase-Based Biocathodes and Stable Biofuel Cells

A modification of electrode surfaces with dispersions of carbon black and consequent enzyme adsorption has been recognized as an efficient technique for construction of biofuel cells (BFCs). To achieve this, typically fluorinated polymers with a negative environmental impact are used as dispersing agents. In this work, these were replaced by an abundant, biodegradable and cost- effective biopolymer poly(lactic acid) (PLA) for construction of novel BFCs in a green and sustainable way. The electron transfer rate of bilirubin oxidase (BOD) within a biocathode, often limiting overall performance of BFCs, was greatly enhanced to the highest value of (300 +/- 2) s(-1) reported so far by introduction of a PLA matrix. The BFC was completed by a combination of a BOD biocathode with a fructose dehydrogenase bioanode, offering a power density of 57. W mu m(-2) at 400 mV. A scanning electron microscopy of scaled up BFC device, prepared by deposition of PLA containing nanocomposites on carbon paper, revealed a highly porous structure, a feature important to deal with a limited diffusion of a biofuel and oxygen within a 3D matrix. The fructose-oxygen BFC offered an excellent operational stability comparable to the best ones reported for similar BFCs with 50% of an initial current/power observed after 10 days of storage.